Liquid pump



Patented July 3, 1928. I

UNITED STATES PATENT OFF IYBON W. DOLE, F BELMONT, MASSACHUSETTS,

- a t 1 v mourn Application filed larch 14,

This invention relates to pum s and has vfor its general object to provie a novel pump for pumping liquid having a temperature approximatelythat of or slightly be ow the vaporizing temperature of the liquid andwhen the available static head on the pump is very small. The ordinaryliquid pump in which the inlet valves are opened b the suction producedby the suction stro e of the piston will not ,functlon properl whenpumping liquid which is at about t e temperature at which the liquidwill vaporize because the suction produced by the suction stroke reducesthe pressure sufiiciently so that the liquid will vaporize,

the va r filling the space behind the iston and t us destroying thesuction wit the result that the pump cylinder will be onlypartially'filled with liquid.

I In order to avoid this difliculty I have provided by my inventionanimdproved 1net valve arrangement for a liqul pump ac- I cording towhich the inlet valve is opened by the pressure developed on thepressure sideof the piston rather than by the suction produced on thesuction side of the,

piston or by steam pressure taken from the ends of the steam c linder.

Other features 0 the invention relate to novel constructions by means ofwhich the vention and showing the piston in mid position Fig. 2 is asectional view through the inlet valve device showing the position ofthe .parts after the piston has reached the end of its stroke and isabout to start its return stroke;

' Fig. 3 is a section similar to Fig.2 but showing the osition of thevalves during the down stro e of the piston. v

Inasmuch as the present invention relates to the inlet valve feature ofa steam-operture but have confined the inustmioa t ated liquid pump Ihave not thought it necessary to show the complete pump.etruc-' Pour.

1m Serial No. 175,045.

the pump cylinder and its piston together with the inlet and outletvalves.

In the drawings 1 indicates the pump cylinder which has therein the pumppiston 2, the latter having a piston rod 3 which is connected to anysuitable motor device by which the piston is reciprocated in the clinder. The pump herein shown is a dou le acting pump and thecylinder'has ports at each end, the ports at one end bein indicated'at 4and those at the other en. at 5. The ports 4 open into a chamber 6formed in the pump casing and the ports communicate with a chamber 7also formed in the pump casing.

The pump is provided with two discharge valves. 8 and 9 that control discharge ports 10 and 11 leading from the chambers 6 and 7 to a dischargechamber 12, the latter having an outlet port (not' discharge valve 8,the discharge valve 9 being closed by its spring and the pressure in thechamber 12. The fluid in the upper end of the cylinder will be forcedout through the ports 4 and the discharge port 10 into the chamber 12and from thence through the outlet port. Similarly, when the piston 2 ismoving downwardly' the pressure below the piston will open-the dischargevalve 9, the discharge valve 8 being automatically closed.

The parts thus far described are or may be all as usual in liquid pumpsand form no part of my present invention which relates to theconstruction of the inlet valves and piston.

. This inlet valve is mounted in an inlet valve chest 14 which isprovided with an induction port 15 leading to a source of supply,

said ort opening into a supply chamber 16. The ihlet valve controlscommunication between the supply chamber 16and the ports at either end 0the cylinder as usual in liquid pumps. The valve herein disclosed,however, is constructed so that it will be shifted from one position toanother by the pressure developed on the pressure side of the pistoninstea suctionside of the piston.-

. The inlet valve structure herein 'g1i5%-;

com rises two valve members 17 and 1890.16:

of by the suction developed on the;

no in storm-of apoppet valve."

member 17 controls a port 19 between the chambers 16 and 6 and the valve18 controls a port 20 which forms communication between the chambers 16and 7. Both valves are mounted on a valve rod 21 which is carried bybearings 22, said rod being adapted to move back and forth axially insaid bearings. Each valve has a limited movement on the valve rod in thedirection of the axis thereof and as shown each valve is formed with thehub portion 23'which fits over and is slidably mounted on a pistonsleeve 24 that is rigid with the valve rod. Each valve is acted on by aseating spring 25 and is limited in its movement relative to the valverod in one direction by its seat and in the other direction by anenlarged end 27 of the iston sleeve 24, said enlarged portion 27 beingin the form of a valve adapted to seat againstthe end 28 of the hub 2?The valve rod 21 carries two collars 26 which engage the valves 17 and18 as the valve rod is shifted thereby to open the valves.

In installing the pump for pumping a liquid which is at about itsvaporizin temperature said pump will be placed 5 ightly below the sourceof supply so that there will be a. small static head in the supplychamber 16.

The operation is as follows. When the pump is at rest and is inactiveboth inlet valves will beclosed by the seating springs 25 as shown in Fi2, the distance between the collars 26 on t e piston rod being properlyproportioned to permit both Valves to be seats at the same time. If nowthe pump is set in operation and the piston begins to move upwardly theliqiud above the piston will be subjected to pressure and as the chamber6 is in free communication with the cylinder the liquid in the chamber 6will also be subjected to this pressure. The pressure of the liquid ainst the piston sleeve 24 on the valve rod wi -be'sufii cient to movethe valve rod downwardlythroughthe valve 17, such movement operatingthrough one of the collars 26 to positively unseat the valve 18 againstthe action of its spring 25 as shown in Fig. 1. As soon as the valve 18is 'unseated the liquid will flow through the induction ort 15 andchamber 16 into the lower end of the cylinder thus filling the cylinder'with liquid as fast as the piston rises.

. During this upstroke of the piston .the liquid in the upper end of thecylinder Willi-be" forced through the discharge port 10 as will bereadily understood.

When the piston reaches the upper limit of its stroke and then begins toreverse the pressure in the chamber 6 will be relieved and there will bean instant when said pressure is the same as that in the chamber 7. Assoon as this occurs the two springs 25 immediately 0811a,; the valve rodand close the lower inlet valve 18 as shown in Fig. 2. As

the pump piston 2 continues its descent and pressure is developedbeneath the piston this pressure will act on the lower end of the pistonsleeve 24 and valve rod and force the same upwardly as shown in Fig. 3thus positively opening the upper inlet valve 17 so that the fluid underits small static head my flow freely through the induction ort 15 andchamber 16 into the upper end 0 the cylinder. When the piston reachesthe lower limit of its movement and then reverses for the upward strokethe inlet valves will again be seated by the springs 25 thus closingboth valves and as the upward movement continues the valve 18 will beopened as above described.

It will be noticed that the opening of either inlet valve' is derived bythe pressure against the end of the piston sleeve in the valve rod whichhas a relatively small crosssectional area. The total pressure on thisrelatively small cross-sectional area will be sufficient to cause thevalve to operate properly but is not of such an amount as to causeinjurious pounding of the valve.

The auxiliary valve seat on the end 27 of each piston sleeve 24 makes atight fit with the end 28 of the hub 23 and thus prevents any leakage atthis point except during the time the valves are in motion.

In order to cushion the action of the'pump piston 2, I will preferablymake each end thereof bevelled slightly as shown at 29 so that as theiston approachesthe end of its stroke in eit er direction the ports 4 or5 will be gradually cut off. By this means the reversing movement of thepiston will be cushioned and a smooth running pump will result.

I claim:

1. In a double-acting pump, in combina-,

tion, a ump cylinder having a piston therein, disc arge rts, aninduction port, an inlet valve device which in one extreme osition openscommunication between sai in-'- duction port and one end of the cylinderwhile maintaining said induction port closed to the other end of thecylinder, and in the other extreme position closes the first-namedcommunication and. opens the second-named communication, and in acentral position closes communication between the induction port andboth ends of the cylinder, and means tending normally to move said valvedevice into central position, said valve device 'when in said centralposition having: p01- to t e PIGS",

tion at least of each end exposed sure in the correspondin end of thecylinder, whereby the valve evice will be automatically centered at theend of each piston stroke and will be positively moved into eitherextreme position by the pressure developed in the cylinder.

2. In a double-acting pump, in combination, a pump cylinder having apiston therecall in, discharge portsila supply chamber, an in- 5. In adouble-acting pump, the combinalet valve device w ich in one extremeposition with a tion 0 ns communication between said supply c amber andone end of the c linder while maintaining said supply 0 amber closed tothe other end of the cylinder, and in the other extreme position closesthe firstnamed communication and opens the secondnamed communication,and in a central position closes communication between the supplychamber and-both ends of the cylinder, means tending normally to holdthe valve device in its central position, and means actuated by the ofthe cylin er to shift the valve device to open the communication betweenthe supply chamber and the other end of the cylin er, whereby the valvedevice will be automaticentered at the end of each piston stro e andwill be positively moved into either extreme position by the pressuredeveloped in the cylinder.

3. In a double-acting pump, the combina- -tion with a cylinder having apiston therein and; provided with discharge ports, of a supply chamber,two poppet valves controlling communication between the sup 1y chamberand the ends of the cylindiar, springs normally holding both valvesclosed, and means actuated by the ressure developed in each end of thecy inder to open the valve which controls communication between the suply chamber and the other end of the cylin er.

4. In a double-acting pump, the combination with a cylinder, a istontherein and discharge ports, of a va ve chest having a supply chambertwo poppet valves controlling commumcation between said sup 1 chamberand the ends of the chamberFZ valve rod on which both valves have alimiting sliding movement, each end of the valve rod being subjected tothe pressure in the corresponding end of the cylinder, and springsnormally holding the poppet valves closed, whereby during the initialmovement of thepiston in either direction the ressure developed b thepiston in one end of the cylinder wil shift the valve rod and therebyopen the valve leading. to the other end of the cylinder. r

ressure developed in each end (pump cylinder having a piston therein andischarge ports, of a valve chest having a supply chamber, two poppetvalves controlling communication between the supply chamber and the endsof the cylinder,

springs normally holding the oppet valves to their seats, and avalve-shi ting member actuated by the pressure developed in each end ofthe cylinder to open the valve leading to the other end of the cylinder,said valve device having an area sub ected to the cylinder' pressurewhich is considerably less than the area of the valve.

' 6; In a double-acting pump, the combinacylinder.

7. In a double-acting pump, the oombination with a cylinder, of a pistontherein, ports leading to and from the cylinder, an inlet valve devicecontrolling the su ply of fluid to the cylinder, means to cause t epressure produced by the piston in each end of the cylinder topositively operate the inlet valve device to permit flow of fluid to theother end of the cylinder, the ends of the piston being tapered, and theports being spaced from the ends of the cylinder, so that the piston mayover-run them, whereby the final movement of the piston in eitherdirection is checked by the increasing resistance which the piston meetsas the tapered portion thereof-closes the V restricts the outflow of thefluid, said piston being prevented from further movement by the fluidtrapped in the end of the cylinder when ports are completely closed.

In testimony whereof, I have signed my name to this specification.

ports and gradually

